com.dimajix.spark.sql.ExpressionParser.scala Maven / Gradle / Ivy

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/*
 * Copyright (C) 2022 The Flowman Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package com.dimajix.spark.sql

import org.apache.spark.sql.catalyst.expressions.Expression
import org.apache.spark.sql.catalyst.expressions.SubqueryExpression
import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
import org.apache.spark.sql.functions.expr


object ExpressionParser {
    def parseExpression(expression:String) : Expression = {
        expr(expression).expr
    }

    /**
     * Analyzes the SQL statement and returns all required dependencies (i.e. table names)
     * @param sql
     * @return
     */
    def resolveDependencies(expression:String) : Set[String] = {
        val plan = parseExpression(expression)
        resolveDependencies(plan)
    }

    def resolveDependencies(expression:Expression) : Set[String] = {
        def collectAllPlans(expression:Expression) : Seq[LogicalPlan] = {
            val plans = expression.collect {
                case q:SubqueryExpression => q.plan
            }
            plans ++ expression.children.flatMap(collectAllPlans)
        }

        val plans = expression.flatMap(collectAllPlans)
        plans.flatMap(SqlParser.resolveDependencies).toSet
    }
}